What is "qjackctl"

QjackCtl is a Qt-based tool for controlling the JACK Audio Connection Kit. QjackCtl is free software released under the GNU GPL v2+.

Basic Functions: It automatically tries to detect audio hardware and lets the user choose subdevices for input and output from a drop-down list as well as common options for the sound server. QjackCtl then uses these selections to build and execute the right command-line for jackd.